Fluorination of acrylate esters and derivatives

ABSTRACT

The present invention generally relates to processes for converting acrylate esters or a derivative thereof to difluoropropionic acid or a derivative thereof. This process is generally performed using fluorine gas in a hydrofluorocarbon solvent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/742,381 filed Jun. 17, 2015, which is a divisional of U.S. patentapplication Ser. No. 14/128,899, filed Feb. 4, 2014 (issued as U.S. Pat.No. 9,061,990), which claims benefit from International PatentApplication No. PCT/US2012/044455, filed Jun. 27, 2012, which claims thebenefit of U.S. Provisional Patent Application Ser. No. 61/501,567,filed Jun. 27, 2011, the entire content of which is incorporated hereinby reference.

FIELD OF THE INVENTION

The present invention generally relates to processes for converting anacrylate ester or a derivative thereof to the correspondingdifluoropropionate or a derivative thereof. The process is generallyperformed using fluorine gas in a hydrofluorocarbon solvent.

BACKGROUND OF THE INVENTION

Potassium (K⁺) is one of the most abundant intracellular cations.Potassium homeostasis is maintained predominantly through the regulationof renal excretion. Various medical conditions, such as decreased renalfunction, genitourinary disease, cancer, severe diabetes mellitus,congestive heart failure and/or the treatment of these conditions canlead to or predispose patients to hyperkalemia. Hyperkalemia can betreated with various cation exchange polymers includingpolyfluoroacrylic acid (polyFAA) as disclosed in WO 2005/097081, WO2010/022381, WO 2010/022382, and WO 2010/022383, each of which isincorporated herein by reference in their entirety.

Polyfluoroacrylic acid can be prepared by polymerization ofalpha-fluoroacrylate esters and derivatives thereof. Although there areseveral methods known for manufacturing the alpha-fluoroacrylic acid oralpha-fluoroacrylate monomer, many of these potential routes ofsynthesis are not commercially reasonable due to over-fluorination orthe costs of the starting materials. It has now been discovered thatcertain process conditions for the direct fluorination of an acrylateester or a derivative thereof using fluorine gas, followed byelimination of hydrogen fluoride, provides the desiredalpha-fluoroacrylic acid or alpha-fluoroacrylate monomer in acommercially efficient and cost effective manner.

SUMMARY OF THE INVENTION

The present invention provides a process for fluorination of acrylateesters or a derivative thereof to form a difluoropropionic acid orderivative thereof.

One of the many aspects of the invention is a process for fluorinating adouble bond that comprises forming a reaction mixture comprising ahydrofluorocarbon solvent, fluorine gas, and a compound of formula 1

to form a compound of formula 2 in a yield of at least 50%

wherein R₁ is hydroxy, alkoxy, chloro, or —OC(O)CH═CH₂ and R₂ ishydroxy, alkoxy, chloro, or —OC(O)CHFCH₂F.

Another aspect is a process for fluorinating a double bond thatcomprises forming a reaction mixture comprising a hydrofluorocarbonsolvent, fluorine gas, and a compound of formula 5

to form a compound of formula 6

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fluorination can be difficult to control and can easily result inproducts that are over fluorinated. Thus, in order to maximize the yieldof desired product and minimize side reactions, the solvent, reactiontemperature, and additives have been found to be significant. It hasbeen found that fluorination of a double bond (e.g., in compounds suchas acrylate esters or derivatives thereof) followed by elimination ofhydrogen fluoride is a commercially feasible process for producingalpha-fluoroacrylate ester.

The process for fluorinating a double bond comprises forming a reactionmixture comprising a hydrofluorocarbon solvent, fluorine gas, and acompound comprising a double bond. The compound comprising a double bondcan be a compound of formula 1

wherein R₁ is hydroxy, alkoxy, chloro, or —OC(O)CH═CH₂. The fluorinationprocess produces the product compound of formula 2

wherein R₂ is hydroxy, alkoxy, chloro, or —OC(O)CHFCH₂F.

R₁ and R₂ include, but are not limited to, hydroxy, alkoxy such asmethoxy, ethoxy, propoxy, 2-propoxy, n-butoxy, iso-butoxy, sec-butoxy,tert-butoxy, n-pentoxy, iso-pentoxy, sec-pentoxy, or tert-pentoxy, orchloro. Preferably, R₁ and R₂ are methoxy, R₁ and R₂ are hydroxy, or R₁and R₂ are chloro.

The compound comprising a double bond can also be a compound of formula

The fluorination process produces the product compound of formula 6

The reaction mixture also comprises fluorine gas. Fluorine gas isgenerally used in a mixture with an inert gas. Examples of such inertgases are nitrogen and helium. The fluorine/inert gas mixture cancontain 1 to 50 mol % of fluorine; about 20 mol % to about 30 mol % offluorine is preferred.

The reaction mixture also comprises a hydrofluorocarbon solvent. Thehydrofluorocarbon solvent comprises 2H,3H-decafluoropentane,eicosafluorononane, tetradecafluorohexane,tetradecafluoro-2-methylpentane, hexafluorobenzene,octadecafluorodecahydronaphthalene, octadecafluorooctane,octafluorocyclopentene, octafluorotoluene,perfluoro(1,3-dimethylcyclohexane), perfluoroheptane,perfluoro(2-butyltetrahydrofuran), perfluorotriethylamine,heptacosafluorotributylamine, tetradecafluoromethylcyclohexane,1,1,1,3,3-pentafluorobutane, or a combination thereof. Preferably, thesolvent comprises 2H,3H-decafluoropentane.

The melting point of the reaction mixture is less than about −20° C.,preferably less than about −40° C.

The boiling point of the reaction mixture can be more than about 30° C.When the hydrofluorocarbon solvent has a melting point greater than thedesired reaction temperature (e.g., −40° C. or −20° C.), another agentcan be added to lower the melting point of the reaction mixture to thedesired temperature. For example, dichloromethane or alcohols such asmethanol or ethanol, and the like can be added to the reaction mixtureto reduce the melting point of the reaction mixture.

Also, the reaction mixture can further comprise a fluorination additive.This fluorination additive can comprise an alcohol, an acid, or acombination thereof. When the fluorination additive comprises analcohol, the alcohol comprises ethanol, methanol, trifluoroethanol, or acombination thereof. When the fluorination additive comprises an acid,the acid comprises triflic acid, trifluoroacetic acid, sulfuric acid,formic acid, acetic acid, or a combination thereof.

Further, the reaction mixture can comprise a hydrogen fluoride (HF)scavenger. The HF scavenger comprises sodium fluoride, potassiumfluoride, cesium fluoride, calcium fluoride, calcium oxide, magnesiumoxide, aluminum oxide, or a combination thereof. Preferably, the HFscavenger comprises sodium fluoride.

The flow rate of introduction of elemental fluorine can be from 0.2mmol/min to 8.3 mmol/min depending on the reaction scale. The flow rateand reaction time are selected to maximize the conversion of (i) thecompound of formula 1 to the compound of formula 2 or (ii) the compoundof formula 5 to the compound of formula 6 while minimizing sidereactions, particularly side reactions producing compounds that areoverfluorinated.

The reaction mixture can contain at least about 1 kg, at least about 5kg, at least about 10 kg, or more of the compound of formula 1 or 5.

The reaction temperature of the process is from about −80° C. to about−20° C. Preferably, the reaction temperature is from about −80° C. toabout −60° C.

The fluorination process can also be performed using a continuousfluorination reactor. Generally, a suitable reactor will include anentry point for the fluorine gas, as well as a temperature controlapparatus. The reactor can be of an appropriate size for the scale ofthe continuous fluorination reaction undertaken. A suitablemicro-reactor is shown in Chambers, R. C. et al., “Microreactors forelemental fluorine,” Chem. Commun., 1999, 883-884, and the design ofsuch reactor is not considered outside the skill of one of ordinaryskill in the art. The reactor can be made of a material that is notreactive with acids, fluorine gas, and other corrosive materials. Forexample, they can be made of stainless steel, Monel, Hasteloy, and thelike.

When carrying out the process described herein using a continuousfluorination reactor, a compound of formula 1 or 5 (e.g., methylacrylate) is dissolved in a solvent (e.g., 2H,3H-decafluoropentane) at aconcentration from about 2 wt. % to about 20 wt. %. This solution ispumped through the reactor at an infusion rate of from about 0.2mL/minute to about 2 mL/minute. When the reaction is taking place, thereactor is placed on a surface that can be reduced in temperature sothat the reactor is at a temperature from about 25° C. to about −80° C.The process can be chilled to about −15° C. At the same time thefluorine gas is passed through the reactor at a gas flow rate of fromabout 0.2 mmol/minute to about 2 mmol/minute. The compound of formula 1or 5 and fluorine gas mix inside the reactor, and the product containingthe compound of formula 2 or 6 is collected in a receiving flask that isfrom about 25° C. to about −80° C., preferably, about −78° C.

The fluorine gas can be diluted before addition to the fluorinationreactor to about 1% fluorine gas in helium to about 20% fluorine gas inhelium.

The residence time of the reactants in the continuous fluorinationreactor can be from about 1 millisecond to about 30 minutes. The meanresidence time is preferably from about 0.5 seconds to about 1 minute,or more preferably from about 1 second to about 10 seconds.

Without being bound by theory, it is believed that the continuousfluorination reactor provides a shorter contact time between thecompound of formula 1 or 5 and the fluorine gas, thus, reducing the overfluorination of the compounds of formula 2 or 6 (e.g., fluorinationproducts).

Once the mixture has reacted to the extent possible to maximize thecontent of the difluoropropionic acid or derivatives thereof, anesterification or a transesterification reaction can be performed. Whenderivatives of formula 2 having R₁ of hydroxy or chloro are formed, anesterification reaction is performed. When derivatives of formula 2having R₁ of alkoxy is formed, a transesterification reaction can beperformed. Each of the reactions can produce the desired alkyldifluoropropanoate by contacting the compound of formula 2 with alcoholand a catalyst. For example, when the methyl difluoropropanoate isdesired, methanol is used as the alcohol.

The catalyst for the transesterification can be an acid or a base. Whenthe transesterification catalyst is an acid, it can be a Bøonsted acidor Lewis acid. Suitable Bøonsted acids include, but are not limited to,toluenesulfonic acid (TsOH), sulfuric acid, hydrochloric acid,phosphoric acid, acetic acid, formic acid, triflic acid, trifluoroaceticacid, or combinations thereof. Suitable Lewis acids include, but are notlimited to, boron tribromide, aluminum oxide, titanium tetraethoxide, orcombinations thereof.

When the catalyst for transesterification is a base, it can be, forexample, dimethylaminopyridine (DMAP), diethylhydroxyamine,triethylamine, N,N-diisopropylethylamine (Hunig's base), pyridine,1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,4-diazabicyclo[2.2.2]octane(DABCO), or a combination thereof. Preferably, the base isdimethylaminopyridine.

For the compound of formula 6, the nitrile group can be transformed toan ester group by reaction with an alcohol and an acid catalyst (i.e.,esterification). Preferably, the alcohol is methanol. The acid catalystcan be a Bøonsted acid or Lewis acid. Suitable Bøonsted acids include,but are not limited to, toluenesulfonic acid (TsOH), sulfuric acid,hydrochloric acid, phosphoric acid, acetic acid, formic acid, triflicacid, trifluoroacetic acid, or combinations thereof. Suitable Lewisacids include, but are not limited to, boron tribromide, aluminum oxide,titanium tetraethoxide, or combinations thereof.

After the esterification or transesterification reaction, the reactionmixture can contain 50 mol %, 55 mol %, 60 mol %, or more of formula 2(wherein R₂ is methoxy) based on the number of moles of formula 1 addedto the reaction mixture.

When the continuous fluorination reactor was used, after theesterification or transesterification reaction, the reaction mixture cancontain 50 mol %, 55 mol %, 60 mol %, or more of formula 2 (wherein R₂is methoxy) based on the number of moles of formula 1 added to thereaction mixture.

The conversion of the 2,3-difluoropropionic acid or a derivative thereofto α-fluoroacrylate ester or a derivative thereof can be achieved byeliminating HF by addition of a base. Exemplary bases include organicamines such as tertiary amines (e.g., dimethylaniline, trimethylamine,1,5-diazabicyclo[4,3,0]non-5-ene (DBN) and1,8-diazabicyclo[5,4,0]undec-7-ene (DBU)), alkoxides, alkali oralkaline-earth hydroxides, or a combination thereof.

For the elimination of HF, a stoichiometrically equivalent base per moleof a compound of Formulae 2 or 6 is used. Typically, 0.8 to 1.2equivalents of base are used for elimination of HF.

The elimination of the HF can be carried out, for example, at reactiontemperatures from about −78° C. to about 180° C.; preferably, from about−20° C. to about 55° C. Ethers, halogenated hydrocarbons and aromaticsolvents can be used as solvents for the elimination of HF reaction.

Unless otherwise indicated, the term “alkoxy,” as used herein alone oras part of another group, denotes an —OX radical, wherein X is asdefined in connection with the term “alkyl.” Exemplary alkoxy moietiesinclude methoxy, ethoxy, propoxy, or 2-propoxy, n-, iso-, ortert-butoxy, and the like.

The alkyl group as described herein is an optionally substituted linearsaturated monovalent hydrocarbon radical containing from one to twentycarbon atoms and preferably one to twelve carbon atoms, or an optionallysubstituted branched saturated monovalent hydrocarbon radical containingthree to twenty carbon atoms, and preferably three to eight carbonatoms. Examples of unsubstituted alkyl groups include methyl, ethyl,n-propyl, propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl,i-pentyl, s-pentyl, t-pentyl, and the like.

The term “substituted” as in “substituted alkyl,” and the like, meansthat in the group in question (i.e., the alkyl or other group thatfollows the term), at least one hydrogen atom bound to a carbon atom isreplaced with one or more substituent groups such as hydroxy (—OH),alkylthio, phosphino, amido (—CON(R_(A))(R_(B)), wherein R_(A) and R_(B)are independently hydrogen, alkyl, or aryl), amino (—N(R_(A))(R_(B)),wherein R_(A) and R_(B) are independently hydrogen, alkyl, or aryl),halo (fluoro, chloro, bromo, or iodo), silyl, nitro (—NO₂), an ether(—OR_(A) wherein R_(A) is alkyl or aryl), an ester (—OC(O)R_(A) whereinR_(A) is alkyl or aryl), keto (—C(O)R_(A) wherein R_(A) is alkyl oraryl), heterocyclo, and the like. When the term “substituted” introducesa list of possible substituted groups, it is intended that the termapply to every member of that group.

Having described the invention in detail, it will be apparent thatmodifications and variations are possible without departing from thescope of the invention defined in the appended claims.

EXAMPLES

The following non-limiting examples are provided to further illustratethe present invention.

General Procedure for Fluorination of Methyl Acrylate.

The fluorine line setup was described in Organic Synthesis, Coll. Vol.8, p. 286-295 (1993) by Teruo Umemoto, Kyoichi Tomita and Kosuke Kawada.All the work was conducted in an efficient fume hood with a fluorine gasdetector in the hood. A cylinder of premixed 20% fluorine in helium wasobtained from Matheson Tri-gas, Inc. The reaction was monitored by GC/MSon a DB-5 column.

Example 1 General Procedure for the Synthesis of Methyl2,3-Difluoropropanoate (B)

A 100-mL round-bottomed reaction flask was charged with methyl acrylateand solvent. The system was purged with helium. The reaction was chilledto −78° C. in a dry ice/acetone bath. A slow stream of 20% fluorine inhelium was introduced to the bottom of the flask under vigorousstirring. The flow rate was adjusted to 47.2 mL/min (0.39 mmol/min) andmaintained at this rate while keeping the reaction at −78° C. for 2hours. The reaction was then purged with helium and warmed to roomtemperature. Solvent was removed. GC/MS was used to analyze thereaction. When assuming the same response factor for each compound, theproduct mixture contained 46.8 wt. % of desired product, methyl2,3-difluoropropanoate (B), along with 4.5 wt. % of starting material(A), 13.8 wt. % of methyl 2,3,3-trifluoropropanoate (D), 11.7 wt. % offluoromethyl 2,3,3-trifluoropropanoate (E), and 23.2 wt. % offluoromethyl 2,3-difluoropropanoate (C).

TABLE 1 Experimental conditions using different solvents, temperatures,and fluorine concentrations Experi- Starting Amount Temp F₂ F₂ mentmaterial (mol) Solvent (° C.) Conc Equiv. 1 A 0.033 acetonitrile 50 −1520% 1.8 mL 2 A 0.022 acetonitrile 50 −40 20% 2.3 mL 3 A 0.022 Dichloro-60 −78 20% 2.1 methane mL 4 A 0.022 Pentafluoro- 60 −15 20% 2.1 butanemL 5 A 0.022 2H,3H- 60 −78 20% 2.1 decafluoro- mL pentane 6 A 0.0222H,3H- 60 −40 20% 2.1 decafluoro- mL pentane 7 A 0.022 2H,3H- 60 −78 10%2.1 decafluoro- mL pentane

TABLE 2 Results of using different solvents, temperatures and fluorineconcentrations Product distribution (area %) Experiment A B C D E 1 45.813.4 2 63.1 11.8 3 61.8 18.4 4 12.9 27.1 4.2 5 14.9 35.5 18.4 14.5 11.56 3.1 33.6 20 18.5 14.6 7 28.4 37.9 15 11.1 7.6

TABLE 3 Experimental conditions using different additives and solventcombinations All reactions were conducted at −78° C. using 20% fluorinein helium Starting Amount Experiment material (mol) Solvent F₂ Equiv. 8A 0.022 2H,3H- 50 mL:0.1 mL 2.5 decafluoropentane:ethanol 9 A 0.0222H,3H- 60 mL:1 mL 2.5 decafluoropentane:ethanol 10 A 0.022 2H,3H- 50mL:0.5 mL 2.5 decafluoropentane:CF₃SO₃H 11 A 0.022 2H,3H- 50 mL:5 mL 2.5decafluoropentane:methanol 12 A 0.022 2H,3H- 30 mL:30 mL 2.5decafluoropentane:dichloromethane 13 A 0.022 2H,3H- 50 mL:1 mL 2.5decafluoropentane:2,2,2- trifluoroethanol

TABLE 4 Results from different additives and solvent combinationsProduct Distribution (area %) Experiment A B C D E 8 17.7 44.1 15.8 9.736.1 9 11.4 48.5 14 14.2 6.1 10 16.2 30.8 15.4 15.1 11.7 11 32.8 39.9 5.57.8 12 27.2 13.5 1.6 13 33 37.7 11.3 9.8 6

Example 2 Synthesis of 2,3-Difluoropropionic Acid (G)

To a solution of acrylic acid in 2H,3H-decafluoropentane was addedsodium fluoride as scavenger for HF. The suspension was cooled to −78°C. under vigorous stirring. Fluorine was introduced to the mixture underthe same conditions as example 1. After the reaction, the mixture wasfiltered and analyzed by GC/MS.

Example 3 Synthesis of Methyl 2,3-Difluoropropanoate (B) Via AcryloylChloride

To a solution of acryloyl chloride in 2H,3H-decafluoropentane was addedsodium fluoride as HF scavenger. The suspension was cooled to −78° C.under vigorous stirring. Fluorine was introduced to the mixture underthe same conditions described in example 1. After the reaction, themixture was filtered. Sodium carbonate (Na₂CO₃) was added to thefiltrate followed by methanol at 0-4° C. The reaction was stirred atroom temperature for 2 hours. The mixture was filtered and analyzed byGC/MS.

Example 4 Synthesis of 2,3-Difluoropropanenitrile (L)

A solution of acrylonitrile in 2H,3H-decafluoropentane was cooled to−78° C. Fluorine was introduced to the mixture under the same conditionsdescribed in example 1. After removal of solvent, the mixture wasanalyzed by GC/MS.

TABLE 5 Experimental conditions of examples 2-4 All reactions wereconducted at −78° C. using 20% fluorine in helium Starting Amount F₂Experiment Material (mol) Solvent Equivalent 14 F 0.029 2H,3H- 50 mL 1.6decafluoropentane NaF (2.44 g, 0.058 mol) 15 J 0.025 2H,3H- 60 mL 2.8decafluoropentane NaF (2.1 g, 0.05 mol) 16 K 0.0304 2H,3H- 60 mL 2.3decafluoropentane

TABLE 6 Results of using different starting materials Experiment ProductDistribution (area %) F G H I 14 40.5 40 10.8 5.8 A B D 15 15.2 43.512.5 K L M 16 38.2 24.3 10.7

Example 5 Transesterification

To a solution of 2 mL of fluorination reaction mixture was addedmethanol and a catalyst. The reaction was stirred at room temperaturefor 48 hours and analyzed by GC/MS.

TABLE 7 Results for transesterification Product Distribution (area %)Experiment Catalyst Amount A E D C B 17 18.35 7.06 10.42 14.17 35.37 18TsOH 5 mg 19.75 0.00 18.42 0.37 48.23 19 DMAP 10 mg 19.54 0.00 18.461.72 46.75 20 H₂SO₄ 50 μL 19.23 0.00 17.74 0.51 47.63 (98%)

To a solution of 2 mL of reaction mixture from direct fluorination wasadded ROH or methanol and a catalyst. The reaction was stirred at roomtemperature for 24 hours and analyzed by GC/MS.

Product Distribution (area %) Experiment R ROH N O B 21 Et EtOH 41.4 39MeOH 36.3 9 43.9 22 n-Bu n-BuOH 47.1 43.7 MeOH 38.3 7.6 28.2

Example 6 Synthesis of Methyl 2,3-Difluoropropanoate

Ethyl acrylate (2 mL) was mixed with 50 mL 2H,3H-Decafluoropentane andcooled in an isopropanol/dry ice bath (−78° C.). The solution wastreated with fluorine (20% in helium) at a fluorine flow rate of 0.1standard cubic feet per hour (SCFH) for 120 minutes. The overfluorinatedproduct ester was trans-esterified by adding methanol or ethanol andDMAP. The conversion was approximately 60%. The difluoroethyl ester anddifluoro methyl ester were observed by Gas Chromatograph-Mass Spec(GCMS).

Example 7 Synthesis of n-Butyl 2,3-Difluoropropanoate

n-Butyl acrylate (2 mL) was mixed with 50 mL 2H,3H-decafluoropentane andcooled in an isopropanol/dry ice bath (−78° C.). The solution wastreated with fluorine (20% in helium) at a fluorine flow rate of 0.1SCFH for 120 minutes. The overfluorinated product was trans esterifiedby adding methanol and DMAP. The conversion was approximately 40%.n-Butyl 2,3-difluoropropanoate was detected by GCMS.

Example 8 Synthesis of Methyl 2,3-Difluoropropanoate Via t-Butyl2,3-Difluoropropanoate

t-Butyl acrylate (2 mL) was mixed with 50 mL 2H,3H-decafluoropentane andcooled in an isopropanol/dry ice bath (−78° C.). The solution wastreated with fluorine (20% in helium) at a fluorine flow rate of 0.1SCFH for 120 minutes. The overfluorinated product ester was transesterified by adding methanol and DMAP. Gas Chromatography-Mass Spec(GCMS) analysis showed that the starting material was mostly consumed.The mixture was less clean than the methyl acrylate, but the desiredproduct (methyl 2,3-difluoropropanoate) was detected.

Example 9 Continuous Fluorination Process

The continuous fluorination process was tested using a microreactorusing a design similar to that in Chambers, R. C. et al., “Microreactorsfor elemental fluorine,” Chem. Commun., 1999, 883-884. The methylacrylate solution was drawn into a 20 mL syringe, and the solution wasslowly pumped into the reactor using a syringe pump at a defined rate ofaddition. The tube for the fluorine gas was connected to a manifoldsetup that was resistant to corrosion by the fluorine gas. The manifoldalso allows further dilution of the fluorine gas with helium. Thefluorine was supplied as a 20% mixture in helium. The exit stream fromthe reactor was transferred to a round bottom flask chilled at −78° C.using an isopropanol/dry ice bath. There was an outlet from the roundbottom flask that transfers the reaction atmosphere through a tube thatcontains Alumina.

Methyl acrylate (1 mL) was dissolved in 2H,3H-decafluoropentane (20 mL)and slowly pumped at 0.7 mL/minute through the reactor. The reactor wasplaced on a cold surface having a temperature of −15° C. Concurrently,fluorine gas was passed through the reactor at a rate of 0.78mmol/minute. The two streams mix inside the reactor, react, and werecollected in a receiving flask cooled at −78° C. GCMS analysis showedthe desired product as the major peaks (7.6 and 7.9 min) as the methyland fluoromethyl esters. The conversion of reactant was approximately90%.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above methods without departingfrom the scope of the invention, it is intended that all mattercontained in the above description shall be interpreted as illustrativeand not in a limiting sense.

1. A process for fluorinating a double bond comprising: forming areaction mixture comprising a fluorocarbon or hydrofluorocarbon solvent,fluorine gas, and a compound of formula 1

wherein R₁ is hydroxy, alkoxy, chloro, or —OC(O)CH═CH₂ to form acompound of formula 2

wherein R₂ is hydroxy, alkoxy, chloro, —OC(O)CHFCH₂F; and to formmonoflurormethyl 2,3-difluoropropanoate, methyl2,3,3-trifluoropropanoate, fluoromethyl 2,3,3-trifluoropropanoate, or acombination thereof.
 2. The process of claim 1 wherein R₁ is methoxy. 3.The process of claim 1 wherein R₁ is hydroxy.
 4. The process of claim 1wherein R₁ is chloro.
 5. The process of claim 2, wherein R₂ is methoxy.6. (canceled)
 7. The process of claim 1, wherein the hydrofluorocarbonsolvent has a melting point less than about −20° C.
 8. The process ofclaim 1, wherein the reaction mixture is a liquid at a temperature lessthan about −40° C.
 9. The process of claim 1, wherein thehydrofluorocarbon solvent has a boiling point greater than about 30° C.10. The process of claim 1, wherein the hydrofluorocarbon solvent is2H,3H-decafluoropentane, eicosafluorononane, tetradecafluorohexane,tetradecafluoro-2-methylpentane, hexafluorobenzene,octadecafluorodecahydronaphthalene, octadecafluorooctane,octafluorocyclopentene, octafluorotoluene,perfluoro(1,3-dimethylcyclohexane), perfluoroheptane,perfluoro(2-butyltetrahydrofuran), perfluorotriethylamine,heptacosafluorotributylamine, tetradecafluoromethylcyclohexane,1,1,1,3,3-pentafluorobutane, or a combination thereof.
 11. The processof claim 10, wherein the hydrofluorocarbon solvent is2H,3H-decafluoropentane.
 12. The process of claim 10, wherein thereaction mixture has a temperature from about −80° C. to about −20° C.13. The process of claim 12, wherein the reaction mixture has atemperature from about −80° C. to about −60° C.
 14. (canceled)
 15. Theprocess of claim 1, wherein the reaction mixture further comprises afluorination additive and the fluorination additive is an alcohol, anacid, or a combination thereof.
 16. The process of claim 15, wherein thefluorination additive is the alcohol, and the alcohol comprises ethanol,methanol, trifluoroethanol, or a combination thereof.
 17. The process ofclaim 15, wherein the fluorination additive is the acid, and the acidcomprises triflic acid, trifluoroacetic acid, sulfuric acid, formicacid, acetic acid, or a combination thereof.
 18. The process of claim 1,wherein the process is a continuous process and the infusion rate of thecompound of formula 1 or 5 is from about 0.2 to about 2 mL/minute.19.-21. (canceled)
 22. The process of claim 10, further comprisingcontacting the compound of formula 2 with an alcohol and a catalyst,wherein the catalyst is a Bøonsted acid or a Lewis acid. 23.-38.(canceled)
 39. The process of claim 1, wherein methyl2,3,3-trifluoropropanoate, fluoromethyl 2,3,3-trifluoropropanoate, or acombination thereof is formed.
 40. The process of claim 1, whereinmethyl 2,3,3-trifluoropropanoate is formed.